WoWDB

This Achievement is now ONLY available on a single character, If you earn it on one char you will not have it in you FoS Tab on any others, this is to fix a bug where people with alts exulted with the two factions were getting the achievement, which slightly (This is a lie) angered people who spent the time grinding it up. 

If you are aiming for this achi, before you switch make sure to buy and keep at least one Exulted item from the vendor of the faction you are switching from, such as a tabard or one of the epics offered, it has been known to bug out and not award the achievement when you reach exulted with the second faction, This helps speed things up when sorting it out with the GMs, incase any records get messed up etc (you will NOT be able to use or wear the items, but until the achi pops, it is worth keeping) 

This happened to myself and a guild member, however, since i kept the Aldor tabbard, I was able to get the achi from a ticket, My friend... well he had two hell grinds.